Bill Nye And Mark Ruffalo March For Science On Earth Day

In honor of Earth Day, thousands of people all across the country and world participated in the March for Science. The main event took place in D.C. and none other than Bill Nye served as honorary co-chair because, really, who better to lead the march than everyone's favorite science guy?

Ruffalo is one of the most politically active celebrities out there, so it's no surprise that he participated in the March for Science and encouraged his fans to do the same. Major bonus points for this hilarious "Mean Girls" meme.

2. Rachel Bloom

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The Crazy Ex-Girlfriend co-creator/star headed to Silicon Valley to speak out on behalf of science. A fan posted this awesome video of Bloom leading a chant that declared, "science is too nuanced for a simple chant!" Preach.

3. Kenneth Cole

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The fashion designer went big when it came to signage with this perfect billboard.

4. Peter Capaldi

The Doctor Who star marched in London — one of the many major cities across the world that held a March for Science to coincide with the D.C. event.

5. Bill Nye

Bill Nye addressed marchers at the main event in Washington, D.C. If you didn't get to see him speak in D.C., don't be too sad — he's set out to save the world through science with his new Netflix series, Bill Nye Saves the World.

6. Kathy Griffin

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Not only did she participate in the Los Angeles March for Science, but Griffin casually defused a fight on the subway. What a rockstar.

7. Nik Dodani

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The L.A.-based actor, comedian, and activist won the award for "best use of a gif."